Investigating Pollination Theories on Pine Cones

Overview

Seed plants depend on their ability to cross-pollinate for sexual mating. In consequence, natural selection shapes their female reproductive organs to be effective pollen receptors. For wind-pollinated plants, the ability to trap pollen effectively from the wind is key for successful reproduction. This study examines the aerodynamic effects of the pine cone and why it is successful at trapping pollen.

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Image Acquisition

Using a microCT scanner (SkyScan 1170; SkyScan, Kontich, Belgium), we created a model ovulate cone of P. radiata. ScanIP version 2.1.187 and ScanFE version 2.0.11.1 (Simpleware, Exeter, U.K.) were used to re-create a 3D mesh from 256 × 217 × 165 cross-sectional scanner images.

Mesh and Model Generation

The original mesh comprising 40 × 106 cells was analyzed initially on a supercomputer (CSAR, Manchester, U.K.), but subsequent analyses were implemented on a smaller twin-processor machine (Workstar W425-HE; Digital Networks U.K., Ashton-under-Lyne, U.K.) with a reduced mesh of 1.8 × 106 cells generated by subsampling and conversion to a polyhedral mesh.

Simulation

To investigate the aerodynamics of the pine cone, a mesh of the surrounding air was exported to Fluent for computational fluid dynamics (CFD) in Fluent. The resulting simulations found that irrespective of the approach or species studied, no evidence was found that turbine-like aerodynamics made a significant contribution to pollen accumulation, which instead occurred primarily by simple impaction.